People use carrying bags to carry around all sorts of things. There are the purses and handbags of many styles and constructions that virtually all women use for innumerable articles, briefcases and portfolios that office workers use, hand luggage for travel available in a wide range of sizes and styles, and all purpose bags, which are usually soft and made of leather or a fabric. (The term "carrying bags" is used herein in a broad sense to refer to purses, handbags, briefcases, luggage, and all purpose bags, as well as other articles that serve similar purposes, such a duffle bags, backpacks, toiletry cases, money pouches and so forth.) Carrying bags are often called upon to receive more articles than they are intended to hold or bulky articles that do not quite fit into them. Many people, therefore, like to have carrying bags that can expand or deform, and "soft" carrying bags of a fabric, such as canvas, or of natural or synthetic leather are very popular. Purses, portfolios and briefcases having pleated side and end walls that expand and contract, depending on the volume of material put into them, also meet this need.
Stretchable fabrics can be used for carrying bags, but are not entirely satisfactory for at least two reasons. First, stretchable fabrics are subject to mechanical failure, such as by tearing, if they are overloaded and stretched excessively; second, they lack durability against snags and tearing from contacting other objects, abrasion over time (natural wear and tear), and soiling.